Renal Artery Stenosis

Background

Specialists have known for a long time that renal artery stenosis (RAS) is the major cause of renovascular hypertension and that it may account for 1-10% of the 50 million people in the United States who have hypertension.

Apart from its role in the pathogenesis of hypertension, renal artery stenosis is also being increasingly recognized as an important cause of chronic renal insufficiency and end-stage renal disease. In older individuals, atherosclerosis (ATH) is by far the most common etiology of renal artery stenosis.[1, 2] As the renal artery lumen progressively narrows, renal blood flow decreases and eventually compromises renal function and structure.

With the increase in the elderly population and the possible increase in the prevalence of renal artery stenosis and ischemic nephropathy, clinicians dealing with renovascular disease (RVD) need noninvasive diagnostic tools and effective therapeutic measures to resolve the problem successfully. This article explores the natural history of this disorder, the value of a variety of invasive and noninvasive diagnostic procedures, and the consequence of allowing the artery to remain obstructed versus reversing renal artery occlusion.

NextPathophysiology

In patients with ATH, the initiator of endothelial injury is not clear; however, dyslipidemia, hypertension, cigarette smoking, diabetes mellitus, viral infection, immune injury, and increased homocysteine levels may contribute to endothelial injury. In the atherosclerotic lesion site, endothelium permeability to plasma macromolecules (eg, low-density lipoprotein [LDL]) increases, turnover of endothelial cells and smooth muscle cells increases, and intimal macrophages increase. When atherogenic lipoproteins exceed certain critical levels, the mechanical forces may enhance lipoprotein insudation in these regions, leading to early atheromatous lesions.

Renal blood flow is 3- to 5-fold greater than the perfusion to other organs because it drives glomerular capillary filtration. Both glomerular capillary hydrostatic pressure and renal blood flow are important determinants of the glomerular filtration rate (GFR).[3]

In patients with renal artery stenosis, the chronic ischemia produced by the obstruction of renal blood flow produces adaptive changes in the kidney that are more pronounced in the tubular tissue. These changes include atrophy with decreased tubular cell size, patchy inflammation and fibrosis, tubulosclerosis, atrophy of the glomerular capillary tuft, thickening and duplication of the Bowman capsule, and intrarenal arterial medial thickening. In patients with renal artery stenosis, the GFR is dependent on angiotensin II and other modulators that maintain the autoregulation system between the afferent and efferent arteries and can fail to maintain the GFR when renal perfusion pressure drops below 70-85 mm Hg. Significant functional impairment of autoregulation, leading to a decrease in the GFR, is not likely to be observed until arterial luminal narrowing exceeds 50%.

The degree of renal artery stenosis that would justify any attempt at either surgical intervention or radiologic intervention is not known. One study suggested that a ratio of pressure, measured distal to renal artery stenosis, less than 90% relative to aortic pressure, was found to be associated with significant renin release from the affected kidney, renin being measured in the ipsilateral renal vein. This might be useful as a functional measurement of significant renovascular stenosis leading to hypertension and, thus, a marker of those individuals more likely to benefit from angioplasty and stenting.[4, 5]

PreviousNextEpidemiologyFrequencyUnited States

Studies suggest that ischemic nephropathy may be responsible for 5-22% of advanced renal disease in all patients older than 50 years.

Mortality/Morbidity

The consequences of renal artery stenosis are hypertension, which may be particularly difficult to control or may require multiple antihypertensive agents (with increased adverse effects), and progressive loss of renal function (ischemic nephropathy).

In addition, the discovery of atherosclerotic RVD frequently occurs in the setting of generalized vascular disease (ie, cerebral, cardiac, peripheral), with the co-morbidity associated with disease in those vascular beds. Thus, any therapeutic intervention for renal artery stenosis should logically take into account the underlying prognosis associated with these co-morbidities.

Race

RVD is less common in African American patients. The incidence rate in 2 studies of patients with severe hypertension was 27-45% in white persons compared to 8-19% in African American persons.[6]

Sex

While the incidence of atherosclerotic RVD is independent of sex, Crowley et al showed that female sex (as well as older age, elevated serum creatinine level, coronary artery disease, peripheral vascular disease, hypertension, and cerebrovascular disease) is an independent predictor of RVD progression.[7]

Age

In 1964, Holley et al reported data from 295 consecutive autopsies performed in their institution during a 10-month period.[8] The mean age at death was 61 years. The prevalence rate of renal artery stenosis was 27% of 256 cases identified as having history of hypertension, while 56% showed significant stenosis (>50% luminal narrowing), and, among normotensive patients, 17% had severe renal artery stenosis (>80% luminal narrowing). Among those older than 70 years, 62% had severe renal artery stenosis.

Another similar autopsy study reported similar results, with 5% of patients older than 64 years showing severe stenosis; this figure increased to 18% for patients aged 65-74 years and 42% for patients older than 75 years.

PreviousProceed to Clinical Presentation , Renal Artery Stenosis

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Aortic Stenosis

Practice Essentials

Aortic stenosis is the obstruction of blood flow across the aortic valve. Among symptomatic patients with medically treated moderate-to-severe aortic stenosis, mortality from the onset of symptoms is approximately 25% at 1 year and 50% at 2 years. Symptoms of aortic stenosis usually develop gradually after an asymptomatic latent period of 10-20 years.

Essential update: Expanded FDA labeling for transcatheter valve allows alternative access sites

In September 2013, the FDA approved new labeling for the Sapien transcatheter valve, which eliminates references to specific access sites used when implanting the valves (ie, transfemoral and transapical approaches) and allows the use of alternative access sites (eg, subclavian approach).[1, 2] The change in labeling was supported by data from the Transcatheter Valve Therapy Registry and European registries.

Signs and symptoms

The classic triad of symptoms in patients with aortic stenosis is as follows[3] :

Chest pain: Angina pectoris in patients with aortic stenosis is typically precipitated by exertion and relieved by restHeart failure: Symptoms include paroxysmal nocturnal dyspnea, orthopnea, dyspnea on exertion, and shortness of breathSyncope: Often occurs upon exertion when systemic vasodilatation in the presence of a fixed forward stroke volume causes the arterial systolic blood pressure to decline

Systolic hypertension can coexist with aortic stenosis. However, a systolic blood pressure higher than 200 mm Hg is rare in patients with critical aortic stenosis.

In severe aortic stenosis, the carotid arterial pulse typically has a delayed and plateaued peak, decreased amplitude, and gradual downslope (pulsus parvus et tardus).

Other symptoms of aortic stenosis include the following:

Pulsus alternans: Can occur in the presence of left ventricular systolic dysfunctionHyperdynamic left ventricle: Unusual; suggests concomitant aortic regurgitation or mitral regurgitationSoft or normal S1Diminished or absent A2: The presence of a normal or accentuated A2 speaks against the existence of severe aortic stenosisParadoxical splitting of the S2: Resulting from late closure of A2Accentuated P2: In the presence of secondary pulmonary hypertensionEjection click: Common in children and young adults with congenital aortic stenosisProminent S4: Resulting from forceful atrial contraction into a hypertrophied left ventricleSystolic murmur: The classic crescendo-decrescendo systolic murmur of aortic stenosis begins shortly after the first heart sound; the intensity increases toward midsystole and then decreases, with the murmur ending just before the second heart sound

See Clinical Presentation for more detail.

Diagnosis

The following studies are used in the diagnosis and assessment of aortic stenosis:

Serum electrolyte levelsCardiac biomarkersComplete blood countB-type natriuretic peptide: May provide incremental prognostic information for predicting symptom onset in asymptomatic patients with severe aortic stenosis[4] Electrocardiography: Serial ECG can demonstrate the progression of aortic stenosisChest radiographyEchocardiography: 2-dimensional and DopplerCardiac catheterization: Can be used if clinical findings are inconsistent with echocardiogram resultsCoronary angiographyRadionuclide ventriculography: May provide information on LV functionExercise stress testing: Contraindicated in symptomatic patients with severe aortic stenosis

See Workup for more detail.

Management

The only definitive treatment for aortic stenosis is aortic valve replacement. The development of symptoms due to this condition provides a clear indication for replacement.[5, 6]

Emergency care

A patient presenting with uncontrolled heart failure should be treated supportively with oxygen, cardiac and oximetry monitoring, intravenous access, loop diuretics, nitrates (remembering the potential nitrate sensitivity of patients with aortic stenosis), morphine (as needed and tolerated), and noninvasive or invasive ventilatory support (as indicated). Patients with severe heart failure due to aortic stenosis that is resistant to medical management should be considered for urgent surgery.

Pharmacologic therapy

Agents used in the treatment of patients with aortic stenosis include the following:

Digitalis, diuretics, and angiotensin-converting enzyme (ACE) inhibitors: Can be cautiously used in patients with pulmonary congestion Vasodilators: May be used for heart failure and for hypertension but should also be employed with extreme cautionDigoxin, diuretics, ACE inhibitors, or angiotensin receptor blockers[6] : Recommended by the European Society of Cardiology (ESC)/European Association for Cardio-Thoracic Surgery (EACTS) guidelines for patients with heart failure symptoms who are not suitable candidates for surgery or transcatheter aortic valve implantation

Aortic valve replacement

According to American College of Cardiology (ACC)/American Heart Association (AHA) guidelines, candidates for aortic valve replacement include the following patients[7] :

Symptomatic patients with severe aortic stenosisPatients with severe aortic stenosis undergoing coronary artery bypass surgeryPatients with severe aortic stenosis undergoing surgery on the aorta or other heart valvesPatients with severe aortic stenosis and LV systolic dysfunction (ejection fraction

Percutaneous balloon valvuloplasty

Percutaneous balloon valvuloplasty is used as a palliative measure in critically ill adult patients who are not surgical candidates or as a bridge to aortic valve replacement in critically ill patients.

See Treatment and Medication for more detail.

Image libraryCalcific aortic stenosis (parasternal long-axis and short-axis views). NextBackground

Aortic stenosis is the obstruction of blood flow across the aortic valve. Aortic stenosis has several etiologies, including congenital (unicuspid or bicuspid valve), calcific (due to degenerative changes), and rheumatic. Degenerative calcific aortic stenosis is now the leading indication for aortic valve replacement. The favorable long-term outcome following aortic valve surgery and the relatively low operative risk emphasize the importance of an accurate and timely diagnosis (see Prognosis).

Stenotic valves are shown in the images below. Symptoms of aortic stenosis usually develop gradually after an asymptomatic latent period of 10-20 years. Exertional dyspnea or fatigue is the most common initial complaint. Ultimately, most patients experience the classic triad of chest pain, heart failure, and syncope (see History).

Two-dimensional (2D) Doppler echocardiography is the imaging modality of choice to diagnose and estimate the severity of aortic stenosis and localize the level of obstruction (see Workup). The only definitive treatment for aortic stenosis is aortic valve replacement (see Treatment and Management).

Go to Pediatric Valvar Aortic Stenosis, Pediatric Subvalvar Aortic Stenosis, and Pediatric Supravalvar Aortic Stenosis for more complete information on these topics.

PreviousNextPathophysiology

When the aortic valve becomes stenotic, resistance to systolic ejection occurs and a systolic pressure gradient develops between the left ventricle and the aorta. This outflow obstruction leads to an increase in left ventricular (LV) systolic pressure. As a compensatory mechanism to normalize LV wall stress, LV wall thickness increases by parallel replication of sarcomeres, producing concentric hypertrophy. At this stage, the chamber is not dilated and ventricular function is preserved, although diastolic compliance is reduced.

Eventually, however, LV end-diastolic pressure (LVEDP) rises, which causes a corresponding increase in pulmonary capillary arterial pressures and a decrease in cardiac output due to diastolic dysfunction. The contractility of the myocardium may also diminish, which leads to a decrease in cardiac output due to systolic dysfunction. Ultimately, heart failure develops.

In most patients with aortic stenosis, LV systolic function is preserved and cardiac output is maintained for many years despite an elevated LV systolic pressure. Although cardiac output is normal at rest, it often fails to increase appropriately during exercise, which may result in exercise-induced symptoms.

Diastolic dysfunction may occur as a consequence of impaired LV relaxation and/or decreased LV compliance, as a result of increased afterload, LV hypertrophy, or myocardial ischemia. LV hypertrophy often regresses following relief of valvular (also called valvular) obstruction. However, some individuals develop extensive myocardial fibrosis, which may not resolve despite regression of hypertrophy.

In patients with severe aortic stenosis, atrial contraction plays a particularly important role in diastolic filling of the left ventricle. Thus, development of atrial fibrillation in aortic stenosis often leads to heart failure due to an inability to maintain cardiac output.

Increased LV mass, increased LV systolic pressure, and prolongation of the systolic ejection phase all elevate the myocardial oxygen requirement, especially in the subendocardial region. Although coronary blood flow may be normal when corrected for LV mass, coronary flow reserve is often reduced.

Myocardial perfusion is thus compromised by the relative decline in myocardial capillary density and by a reduced diastolic transmyocardial (coronary) perfusion gradient due to elevated LV diastolic pressure. Therefore, the subendocardium is susceptible to underperfusion, which results in myocardial ischemia.

Angina results from a concomitant increased oxygen requirement by the hypertrophic myocardium and diminished oxygen delivery secondary to diminished coronary flow reserve, decreased diastolic perfusion pressure, and relative subendocardial myocardial ischemia.

PreviousNextEtiology

Most cases of aortic stenosis are due to the obstruction at the valvular level. Common causes are summarized in Table 1.

Table 1. Common Causes of Aortic Stenosis Among Patients Requiring Surgery (Open Table in a new window)

Age Age >70 years (n=322) Bicuspid AV (50%)

Postinflammatory (25%)

Degenerative (18%)

Unicommissural (3%)

Hypoplastic (2%)

Indeterminate (2%)

Degenerative (48%)

Bicuspid (27%)

Postinflammatory (23%)

Hypoplastic (2%)

Valvular aortic stenosis can be either congenital or acquired.

Congenital valvular aortic stenosis

Congenitally unicuspid, bicuspid, tricuspid, or even quadricuspid valves may be the cause of aortic stenosis. In neonates and infants younger than 1 year, a unicuspid valve can produce severe obstruction and is the most common anomaly in infants with fatal valvular aortic stenosis. In patients younger than 15 years, unicuspid valves are most frequent in cases of symptomatic aortic stenosis.

In adults who develop symptoms from congenital aortic stenosis, the problem is usually a bicuspid valve. Bicuspid valves do not cause significant narrowing of the aortic orifice during childhood. The altered architecture of the bicuspid aortic valve induces turbulent flow with continuous trauma to the leaflets, ultimately resulting in fibrosis, increased rigidity and calcification of the leaflets, and narrowing of the aortic orifice in adulthood.

A cohort study by Tzemos et al of 642 ambulatory adults with bicuspid aortic valves found that during the mean follow-up duration of 9 years, survival rates were not lower than for the general population. However, young adults with bicuspid aortic valve had a high likelihood of eventually requiring aortic valve intervention.[8]

Congenitally malformed tricuspid aortic valves with unequally sized cusps and commissural fusion (“functionally bicuspid” valves) can also cause turbulent flow leading to fibrosis and, ultimately, to calcification and stenosis. Clinical manifestations of congenital aortic stenosis in adults usually appear after the fourth decade of life.

Acquired valvular aortic stenosis

The main causes of acquired aortic stenosis include degenerative calcification and, less commonly, rheumatic heart disease.

Degenerative calcific aortic stenosis (also called senile calcific aortic stenosis) involves progressive calcification of the leaflet bodies, resulting in limitation of the normal cusp opening during systole. This represents a consequence of long-standing hemodynamic stress on the valve and is currently the most frequent cause of aortic stenosis requiring aortic valve replacement. The calcification may also involve the mitral annulus or extend into the conduction system, resulting in atrioventricular or intraventricular conduction defects.

Risk factors for degenerative calcific aortic stenosis include hypertension, hypercholesterolemia, diabetes mellitus, and smoking. The available data suggest that the development and progression of the disease are due to an active disease process at the cellular and molecular level that shows many similarities with atherosclerosis, ranging from endothelial dysfunction to, ultimately, calcification.[9]

In rheumatic aortic stenosis, the underlying process includes progressive fibrosis of the valve leaflets with varying degrees of commissural fusion, often with retraction of the leaflet edges and, in certain cases, calcification. As a consequence, the rheumatic valve often is regurgitant and stenotic. Coexistent mitral valve disease is common.

Other, infrequent causes of aortic stenosis include obstructive vegetations, homozygous type II hypercholesterolemia, Paget disease, Fabry disease, ochronosis, and irradiation.

It is worthwhile to note that although differentiation between tricuspid and bicuspid aortic stenosis is frequently made, it is often difficult to determine the number of aortic valve leaflets. A study comparing operatively excised aortic valve structure evaluation by cardiac surgeon versus pathologist found that valve structure determination was frequently incongruous.[10]

PreviousNextEpidemiology

Severe aortic stenosis is rare in infancy, occurring in 0.33% of live births, and is due to a unicuspid or bicuspid valve. Most patients with a congenitally bicuspid aortic valve who develop symptoms do not do so until middle age or later. Patients with rheumatic aortic stenosis typically present with symptoms after the sixth decade of life.

Aortic sclerosis (aortic valve calcification without obstruction to blood flow, considered a precursor of calcific degenerative calcific aortic stenosis) increases in incidence with age and is present in 29% of individuals older than 65 years and in 37% of individuals older than 75 years. In elderly persons, the prevalence of aortic stenosis is between 2% and 9%.

Degenerative calcific aortic stenosis usually manifests in individuals older than 75 years and occurs most frequently in males.[5]

PreviousNextPrognosis

Patients with severe aortic stenosis may be asymptomatic for many years despite the presence of severe LV outflow tract obstruction (LVOTO). LVOTOs have been associated with “high heritability.” One study suggests that 20% of patients with isolated LVOTO had an affected first-degree relative with undetected bicuspid aortic valves.[11]

Asymptomatic patients, even with critical aortic stenosis, have an excellent prognosis for survival, with an expected death rate of less than 1% per year; only 4% of sudden cardiac deaths in severe aortic stenosis occur in asymptomatic patients. A new proposed aortic stenosis grading classification that integrates valve area and flow-gradient patterns has been found to allow for better characterization of the clinical outcome among patients with asymptomatic severe aortic stenosis.[12]

Although the presence of low-gradient "severe stenosis" (defined as aortic valve area 2 and mean gradient 40 mm Hg) is considered by some to be associated with a poor prognosis, the prospective Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study found that such patients have an outcome similar to that of patients with moderate stenosis.[13]

Among symptomatic patients with medically treated, moderate-to-severe aortic stenosis, mortality rates from the onset of symptoms are approximately 25% at 1 year and 50% at 2 years. More than 50% of deaths are sudden. In patients in whom the aortic valve obstruction remains unrelieved, the onset of symptoms predicts a poor outcome with medical therapy; the approximate time interval from the onset of symptoms to death is 1.5-2 years for heart failure, 3 years for syncope, and 5 years for angina.

Although the obstruction tends to progress more rapidly in degenerative calcific aortic valve disease than in congenital or rheumatic disease, predicting the rate of progression in individual patients is not possible. Catheterization and echocardiographic studies suggest that, on average, the valve area declines 0.1-0.3 cm2 per year; the systolic pressure gradient across the valve can increase by as much as 10-15 mm Hg per year. Obstruction progresses more rapidly in elderly patients with coronary artery disease and chronic renal insufficiency.

PreviousNextPatient Education

For patient education information, see eMedicineHealth's patient education article Angina Pectoris.

PreviousProceed to Clinical Presentation  Contributor Information and DisclosuresAuthor

Xiushui (Mike) Ren, MD  Cardiologist, The Permanente Medical Group; Associate Director of Research, Cardiovascular Diseases Fellowship, California Pacific Medical Center
Xiushui (Mike) Ren, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, and American Society of Echocardiography
Disclosure: Nothing to disclose.

Chief Editor

Richard A Lange, MD  Professor and Executive Vice Chairman, Department of Medicine, Director, Office of Educational Programs, University of Texas Health Science Center at San Antonio
Richard A Lange, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American Heart Association, and Association of Subspecialty Professors
Disclosure: Nothing to disclose.

Additional Contributors

Jerry Balentine, DO Professor of Emergency Medicine, New York College of Osteopathic Medicine; Executive Vice President, Chief Medical Officer, Attending Physician in Department of Emergency Medicine, St Barnabas Hospital

Jerry Balentine, DO is a member of the following medical societies: American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American College of Physician Executives, American Osteopathic Association, and New York Academy of Medicine

Disclosure: Nothing to disclose.

Edward Bessman, MD, MBA Chairman and Clinical Director, Department of Emergency Medicine, John Hopkins Bayview Medical Center; Assistant Professor, Department of Emergency Medicine, Johns Hopkins University School of Medicine

Edward Bessman, MD, MBA is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

David FM Brown, MD Associate Professor, Division of Emergency Medicine, Harvard Medical School; Vice Chair, Department of Emergency Medicine, Massachusetts General Hospital

David FM Brown, MD is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Steven J Compton, MD, FACC, FACP, FHRS Director of Cardiac Electrophysiology, Alaska Heart Institute, Providence and Alaska Regional Hospitals

Steven J Compton, MD, FACC, FACP, FHRS is a member of the following medical societies: Alaska State Medical Association, American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, and Heart Rhythm Society

Disclosure: Nothing to disclose.

Daniel P Lombardi, DO Clinical Assistant Professor, New York College of Osteopathic Medicine; Attending Physician, Associate Department Director and Program Director, Department of Emergency Medicine, St Barnabas Hospital

Daniel P Lombardi, DO is a member of the following medical societies: American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, and American Osteopathic Association

Disclosure: Nothing to disclose.

John A McPherson, MD, FACC, FAHA, FSCAI Associate Professor of Medicine, Division of Cardiovascular Medicine, Director of Cardiovascular Intensive Care Unit, Vanderbilt Heart and Vascular Institute

John A McPherson, MD, FACC, FAHA, FSCAI is a member of the following medical societies: Alpha Omega Alpha, American College of Cardiology, American Heart Association, Society for Cardiac Angiography and Interventions, Society of Critical Care Medicine, and Tennessee Medical Association

Disclosure: Abbott Vascular Corp. Consulting fee Consulting

Bekir H Melek, MD, FACC Assistant Professor of Clinical Medicine, Department of Medicine, Section of Cardiology, Tulane University School of Medicine

Disclosure: Nothing to disclose.

Gary Setnik, MD Chair, Department of Emergency Medicine, Mount Auburn Hospital; Assistant Professor, Division of Emergency Medicine, Harvard Medical School

Gary Setnik, MD is a member of the following medical societies: American College of Emergency Physicians, National Association of EMS Physicians, and Society for Academic Emergency Medicine

Disclosure: SironaHealth Salary Management position; South Middlesex EMS Consortium Salary Management position; ProceduresConsult.com Royalty Other

James V Talano, MD, MM, FACC Director of Cardiovascular Medicine, SWICFT Institute

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

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Rossebo AB, Pedersen TR, Boman K, et al. Intensive lipid lowering with simvastatin and ezetimibe in aortic stenosis. N Engl J Med. Sep 25 2008;359(13):1343-56. [Medline].

Cowell SJ, Newby DE, Prescott RJ, et al. A randomized trial of intensive lipid-lowering therapy in calcific aortic stenosis. N Engl J Med. Jun 9 2005;352(23):2389-97. [Medline].

[Guideline] Wann LS, Curtis AB, Ellenbogen KA, et al. 2011 ACCF/AHA/HRS Focused Update on the Management of Patients With Atrial Fibrillation (Update on Dabigatran): A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. Mar 15 2011;123(10):1144-50. [Medline]. [Full Text].

[Best Evidence] Bagur R, Webb JG, Nietlispach F, Dumont E, De Larochellière R, Doyle D, et al. Acute kidney injury following transcatheter aortic valve implantation: predictive factors, prognostic value, and comparison with surgical aortic valve replacement. Eur Heart J. Apr 2010;31(7):865-74. [Medline]. [Full Text].

Eltchaninoff H, Prat A, Gilard M et al,. Transcatheter aortic valve implantation: early results of the FRANCE (FRench Aortic National CoreValve and Edwards) registry. Eur Heart Jl. 2011;32:191–197.

Lefevre T, Kappetein AP, Wolner E, et al. One year follow-up of the multi-centre European PARTNER transcatheter heart valve study. Eur Heart Jl. 2011;32:148–157.

Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med. Oct 21 2010;363(17):1597-607. [Medline].

Prasad Y, Bhalodkar NC. Aortic sclerosis--a marker of coronary atherosclerosis. Clin Cardiol. Dec 2004;27(12):671-3. [Medline].

[Best Evidence] Rosenhek R, Zilberszac R, Schemper M, Czerny M, Mundigler G, Graf S, et al. Natural history of very severe aortic stenosis. Circulation. Jan 5 2010;121(1):151-6. [Medline].

Tamburino C, Capodanno D, Ramondo A, Petronio AS, Ettori F, Santoro G, et al. Incidence and predictors of early and late mortality after transcatheter aortic valve implantation in 663 patients with severe aortic stenosis. Circulation. Jan 25 2011;123(3):299-308. [Medline].

Zahn R, Gerckens U, EGrube E et al. Transcatheter aortic valve implantation: first results from a multi-centre real-world registry. Eur Heart Jl. 2011;32:198–204.

Zajarias A, Cribier AG. Outcomes and safety of percutaneous aortic valve replacement. J Am Coll Cardiol. May 19 2009;53(20):1829-36. [Medline].

  Calcific aortic stenosis (parasternal long-axis and short-axis views). Stenotic aortic valve (macroscopic appearance). Table 1. Common Causes of Aortic Stenosis Among Patients Requiring SurgeryTable 2. ACC/AHA Recommendations for Echocardiography (Imaging, Spectral, and Color Doppler) in Aortic StenosisTable 3. Criteria for Determining Severity of Aortic StenosisTable 4. Recommendations for Cardiac Catheterization in Aortic StenosisTable 5. Recommendations for Aortic Valve Replacement in Aortic StenosisTable 1. Common Causes of Aortic Stenosis Among Patients Requiring SurgeryAge Age >70 years (n=322) Bicuspid AV (50%)

Postinflammatory (25%)

Degenerative (18%)

Unicommissural (3%)

Hypoplastic (2%)

Indeterminate (2%)

Degenerative (48%)

Bicuspid (27%)

Postinflammatory (23%)

Hypoplastic (2%)

Table 2. ACC/AHA Recommendations for Echocardiography (Imaging, Spectral, and Color Doppler) in Aortic StenosisIndication Class Diagnosis and assessment of severity of aortic stenosisIAssessment of LV size, function, and/or hemodynamicsIReevaluation of patients with known aortic stenosis with changing symptoms or signsIAssessment of changes in hemodynamic severity and ventricular function in patients with known aortic stenosis during pregnancyIReevaluation of asymptomatic patients with severe aortic stenosisIReevaluation of asymptomatic patients with mild to moderate aortic stenosis and evidence of LV dysfunction or hypertrophyIIaRoutine reevaluation of asymptomatic adult patients with mild aortic stenosis who have stable physical signs and normal LV size and function IIITable 3. Criteria for Determining Severity of Aortic StenosisSeverity Mean gradient (mm Hg) Aortic valve area (cm2) Mild>1.5Moderate25-401-1.5Severe>40
(or 2/m2 body surface area)

Critical>80Table 4. Recommendations for Cardiac Catheterization in Aortic StenosisIndication Class Coronary angiography before aortic valve replacement in patients at risk for coronary artery diseaseIAssessment of severity of aortic stenosis in symptomatic patients when aortic valve replacement is planned or when noninvasive tests are inconclusive or a discrepancy exists in the clinical findings regarding the severity of aortic stenosis or the need for surgery ICoronary angiography before aortic valve replacement in patients for whom a pulmonary autograft (Ross procedure) is contemplated and the origin of the coronary arteries was not identified by noninvasive tests IWith infusion of dobutamine, can be useful for evaluation of patients with low-flow/low-gradient aortic stenosis and LV dysfunctionIIaNot recommended for hemodynamic measurements for assessment of aortic stenosis severity when noninvasive techniques are adequate and concord with clinical findings IIINot recommended for hemodynamic measurements for assessment of LV function and aortic stenosis severity in asymptomatic patientsIIITable 5. Recommendations for Aortic Valve Replacement in Aortic StenosisIndication Class Symptomatic patients with severe aortic stenosisIPatients with severe aortic stenosis undergoing coronary artery bypass surgeryIPatients with severe aortic stenosis undergoing surgery on the aorta or other heart valvesIPatients with severe aortic stenosis and LV systolic dysfunction (ejection fraction IPatients with moderate aortic stenosis undergoing coronary artery bypass surgery or surgery on the aorta or other heart valvesIIaPatients with mild aortic stenosis undergoing coronary artery bypass surgery when there is evidence that progression may be rapid, such as moderate-to-severe valve calcificationIIbAsymptomatic patients with severe aortic stenosis and abnormal response to exercise (eg, hypotension)IIbAsymptomatic patients with severe aortic stenosis and a high likelihood of rapid progression (based on age, calcification, and coronary artery disease) or if surgery might be delayed at the time of symptom onsetIIbAsymptomatic patients with extremely severe aortic stenosis (valve area less than 0.6 cm2, mean gradient greater than 60 mm Hg, and jet velocity greater than 5 m per second) if the patient’s expected operative mortality is 1% or lessIIbAVR is not useful for prevention of sudden death in asymptomatic patients with none of the findings listed under asymptomatic patients with severe aortic stenosisIII View Table List  Read more about Aortic Stenosis on MedscapeRelated Reference Topics
Aortic Stenosis Pathology
Pediatric Supravalvar Aortic Stenosis
Pediatric Valvar Aortic Stenosis
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Medscape Reference © 2011 WebMD, LLC, Aortic Stenosis

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Mitral Stenosis

Background

Mitral stenosis (MS) is characterized by obstruction to left ventricular inflow at the level of mitral valve due to structural abnormality of the mitral valve apparatus. The most common cause of mitral stenosis is rheumatic fever. Other less common etiologies include congenital mitral stenosis, malignant carcinoid disease, systemic lupus erythematosus, rheumatoid arthritis, mucopolysaccharidoses of the Hunter-Hurler phenotype, Fabry disease, Whipple disease, and methysergide therapy. The association of atrial septal defect with rheumatic mitral stenosis is called Lutembacher syndrome.

A number of conditions can simulate the physiology of mitral stenosis: severe nonrheumatic mitral annular calcification, infective endocarditis with large vegetation, left atrial myxoma, ball valve thrombus, or cor triatriatum.

Stenosis of the mitral valve typically occurs decades after the episode of acute rheumatic carditis. Acute insult leads to formation of multiple inflammatory foci (Aschoff bodies, perivascular mononuclear infiltrate) in the endocardium and myocardium. Small vegetations along the border of the valves may also be observed. With time, the valve apparatus becomes thickened, calcified, and contracted, and commissural adhesion occurs, ultimately resulting in stenosis.

Whether the progression of valve damage is due to hemodynamic injury of the already affected valve apparatus or to the chronic inflammatory nature of the rheumatic process is unclear.

NextPathophysiology

The normal mitral valve orifice area is approximately 4-6 cm2. As the orifice size decreases, the pressure gradient across the mitral valve increases to maintain adequate flow.

Patients will not experience valve-related symptoms until the valve area is 2-2.5 cm2 or less, at which point moderate exercise or tachycardia may result in exertional dyspnea from the increased transmitral gradient and left atrial pressure.

Severe mitral stenosis occurs with a valve area of less than 1 cm2. As the valve progressively narrows, the resting diastolic mitral valve gradient, and hence left atrial pressure, increases. This leads to transudation of fluid into the lung interstitium and dyspnea at rest or with minimal exertion. Hemoptysis may occur if the bronchial veins rupture and left atrial dilatation increases the risk for atrial fibrillation and subsequent thromboembolism.

Pulmonary hypertension may develop as a result of (1) retrograde transmission of left atrial pressure, (2) pulmonary arteriolar constriction, (3) interstitial edema, or (4) obliterative changes in the pulmonary vascular bed (intimal hyperplasia and medial hypertrophy). As pulmonary arterial pressure increases, right ventricular dilation and tricuspid regurgitation may develop, leading to elevated jugular venous pressure, liver congestion, ascites, and pedal edema.

Left ventricular end-diastolic pressure and cardiac output are usually normal in the person with isolated mitral stenosis. As the severity of stenosis increases, the cardiac output becomes subnormal at rest and fails to increase during exercise. Approximately one third of patients with rheumatic mitral stenosis have depressed left ventricular systolic function as a result of chronic rheumatic myocarditis. The presence of concomitant mitral regurgitation, systemic hypertension, aortic stenosis, or myocardial infarction can also adversely affect left ventricular function and cardiac output.

PreviousNextEpidemiologyFrequencyUnited States

The prevalence of rheumatic disease in developed nations is steadily declining with an estimated incidence of 1 in 100,000.

International

The prevalence of rheumatic disease is higher in developing nations than in the United States.[1] In India, for example, the prevalence is approximately 100-150 cases per 100,000, and in Africa the prevalence is 35 cases per 100,000.

Mortality/Morbidity

Mitral stenosis is a progressive disease consisting of a slow, stable course in the early years followed by an accelerated course later in life. Typically, there is a latent period of 20-40 years from the occurrence of rheumatic fever to the onset of symptoms. Once symptoms develop, it is almost a decade before they become disabling. In some geographic areas, mitral stenosis progresses more rapidly, presumably due to either a more severe rheumatic insult or repeated episodes of rheumatic carditis due to new streptococcal infections, which results in severe symptomatic mitral stenosis in the late teens and early 20s.

In the asymptomatic or minimally symptomatic patient, survival is greater than 80% at 10 years. When limiting symptoms occur, 10-year survival is less than 15% in the patient with untreated mitral stenosis. When severe pulmonary hypertension develops, mean survival is less than 3 years. Most (60%) patients with severe untreated mitral stenosis die of progressive pulmonary or systemic congestion, but others may suffer systemic embolism (20-30%), pulmonary embolism (10%), or infection (1-5%).

Sex

Two thirds of all patients with rheumatic mitral stenosis are female.

Age

The onset of symptoms usually occurs between the third and fourth decade of life.

PreviousProceed to Clinical Presentation , Mitral Stenosis

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Pulmonic Valvular Stenosis

Background

Pulmonic valvular stenosis (PVS) is described as lesions that collectively are associated with obstruction to the right ventricular outflow tract. Stenosis may be valvular, subvalvular, or supravalvular. Isolated pulmonary stenosis is considered to be a rare congenital abnormality.[1] It is the most common cause of congenital outflow tract obstruction, resulting in decreased flow from the right ventricle to the pulmonary arteries.[2] Isolated right ventricular outflow tract obstruction is pulmonic valvular stenosis in 80% of cases.[3]

Pulmonic valvular disease is clinically detected at different stages of life. The more severe the obstruction, the earlier the valvular abnormality is detected. Pulmonic valvular stenosis is most often associated with the failure of the valvular leaflets to fuse and less commonly is caused by dysplastic thickening of the valves.[4]

Neonates with critical stenosis typically present with central cyanosis at birth. Infants and children with ejection murmurs auscultated in the pulmonic area are often evaluated, and stenosis is discovered during this period. Symptoms of pulmonic stenosis have been observed to progress with time.[5] Adults present with symptoms of congestive heart failure (CHF) and right ventricular outflow obstruction that is progressive in nature.[6] Many of these congenital valvular malformations occur in the setting of well-defined syndromes. Examples of such syndromes involving stenosis of the pulmonic valves are Holt-Oram syndrome, Noonan syndrome, and Leopard syndrome.[5, 7] Eisenmenger syndrome associated with trisomy 13 also results in pulmonary outflow tract obstruction; however, often, other cardiac malformations are involved as well.[8]

A large study called the Second Natural History Study of Congenital Heart Defects analyzed the treatment, quality of life, echocardiography findings, complications, exercise responses, and predisposition to endocarditis with regards to cardiac valvular disease, and pulmonary stenosis was found to be the most benign valvular lesion.[9]

NextPathophysiology

Supravalvular, valvular, and subvalvular lesions are associated with pulmonic valvular stenosis. Lesions vary in severity, from with simple valvular hypertrophy to complete outflow obstruction and atresia.[6] The trileaflet pulmonic valve ranges from thickened or partially fused commissures to an imperforate valve.

Most cases of pulmonic valvular stenosis are congenital. Often times, the valvular abnormality is associated with syndromes such as Noonan syndrome and Leopard syndrome. The inheritance pattern of pulmonic valvular stenosis is poorly understood, although these syndromes display an autosomal dominant pattern. Rarely, pulmonic stenosis is associated with recessively transmitted conditions such as Laurence-Moon-Biedl syndrome. Mutations in germlines PTPN1 and RAF1 have been associated with these valvular abnormalities.[10] Supravalvular lesion may occur in the setting of tetralogy of Fallot, Williams syndrome, Alagille syndrome, as well as Noonan syndrome.[6]

The myocardial cushion begins as a matrix of endothelial cells and an outer mitochondrial layer separated by cardiac jelly. After endocardial cushion formation, the endothelial mesenchymal transformation (EMT), which are specified endothelial cells, differentiate and migrate into the cardiac jelly. Through a poorly understood process, the cardiac jelly goes through local expansion and bolus swelling, and cardiac valves are formed. The aortic and pulmonic valves develop from the outflow tract of the endocardial cushion, also believed to have neural crest cell migration from the brachial crest during development.[5]

Research suggests that the vascular endothelial growth factor (VEGF), a pleiotropic factor, is responsible for signaling the development of the endocardial cushion. Hypoxia and glucose have regulatory effects on this factor. Infants born to hyperglycemic mothers have a 3-fold increase in cardiovascular abnormalities. There has been correlation between intrapartum hypoxic events and valvular disease. Additionally, numerous signaling molecules contribute to VEGF and EMT such as the ERB-B signaling in the cardiac jelly, transforming growth factor (TGF)/cadherin, and BMP/TGF-beta.[5]

The pulmonic valve develops between the 6th and 9th week of gestation. Normally, the pulmonic valve is formed from 3 swellings of subendocardial tissue called the semilunar valves. These tubercles develop around the orifice of the pulmonary tree. The swellings are normally hollowed out and reshaped to form the 3 thin-walled cusps of the pulmonary valve. In Noonan syndrome, tissue pad overgrowth within the sinuses interferes with the normal mobility and function of the valve.

Failure to develop normally can result in the following malformations: fusion of 2 of the cusps, 3 leaflets that are thickened and partially fused at the commissures, or a single cone-shaped valve.

In the congenital rubella syndrome, supravalvular pulmonic and pulmonary artery branch stenoses are frequently present. Acquired valvular disease is rare. The most common etiologies are carcinoid syndrome, rheumatic fever, and homograft dysfunction.[4]

Years of stenosis can result in subendocardial hypertrophy causing significant outflow obstruction and resulting in right ventricular pressure overload and pulmonary hypertension. As this process worsens, the asymptomatic adult becomes gradually symptomatic.[11, 12]

PreviousNextEpidemiologyFrequencyUnited States

Approximately 5 out of 1000 infants are born with a congenital cardiac malformation.[5] Cardiac malformation is the most common congenital abnormality. Among cardiac malformations, valvular defects are the most common subtype, accounting for 25% of all malformations involving the myocardium.[5] Prevalence of pulmonary stenosis is 8-12% of all congenital heart defects.

Isolated pulmonic valvular stenosis with intact ventricular septum is the second most common congenital cardiac defect. Pulmonic valvular stenosis may occur in as many as 30% of all patients who have other congenital heart defects.

Sixty percent of patients with Noonan syndrome are found to have some degree of pulmonic valvular stenosis.[7]

Mortality/Morbidity

Valvular disease in general has high morbidity and mortality rates. Isolated pulmonic valvular disease has been found to be the most benign.[9] In the United States, about 82,000 valvular replacements are performed per year.[5] Survival to adulthood is most common, as symptoms and extent of disease progress with time.[2]

Much of what is known about the morbidity and mortality of pulmonic valvular stenosis comes from the Natural History Study of Congenital Heart Defects and the Second Natural History Study of Congenital Heart Defects. The Natural History Study of Congenital Heart Defects included an initial cardiac catheterization and then follow up for events over an 8-year period. The Second Natural History Study of Congenital Heart Defects reported on 16-27 years of follow up from the same cohort.[9]

The studies demonstrated that adverse outcomes directly relate to the right ventricular systolic pressure gradient.[13] Mild pulmonic valvular stenosis with pressure gradient across the valve less than 50 mm Hg was found to be well tolerated clinically and subjectively.[9] Of these patients, 94% were asymptomatic, without cyanosis or congestive heart failure.[14, 15] Moderate-to-severe pulmonic valvular stenosis, with pressure gradient greater than 50 mm Hg is more often associated with decreased cardiac output, right ventricular hypertrophy, early congestive heart failure (CHF), and cyanosis. Valvulotomy has been shown to improve morbidity and mortality and is indicated with these gradients.[9]

The morbidity and mortality of valvular lesions in regards to pregnancy and fetal outcomes has not been rigorously studied. A case-control study of 17 patients suggested that there is no adverse impact on either the mother or the fetus.[16]

Sex

The male-to-female ratio of pulmonic valvular stenosis is approximately 1:1.

Age

Pulmonic valvular stenosis most commonly presents in newborns. It can be asymptomatic for years.

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Pulmonic Stenosis

Background

Pulmonic stenosis (PS) refers to a dynamic or fixed anatomic obstruction to flow from the right ventricle (RV) to the pulmonary arterial vasculature. Although most commonly diagnosed and treated in the pediatric population, individuals with complex congenital heart disease and more severe forms of isolated PS are surviving into adulthood and require ongoing assessment and cardiovascular care.

NextPathophysiology

PS can be due to isolated valvular (90%), subvalvular, or peripheral (supravalvular) obstruction, or it may be found in association with more complicated congenital heart disorders. The characteristics of the various types of PS are described in this section.[1]

Valvular pulmonic stenosis

Isolated valvular PS comprises approximately 10% of all congenital heart disease. Typically, the valve commisures are partially fused and the 3 leaflets are thin and pliant, resulting in a conical or dome-shaped structure with a narrowed central orifice. Poststenotic pulmonary artery dilatation may occur owing to "jet-effect" hemodynamics.

Alternatively, approximately 10-15% of individuals with valvar PS have dysplastic pulmonic valves. These valves have irregularly shaped, thickened leaflets, with little, if any, commissural fusion, and they exhibit variably reduced mobility. The leaflets are composed of myxomatous tissue, which may extend to the vessel wall. The valve annulus is usually small, and the supravalvular area of the pulmonary trunk is usually hypoplastic. Poststenotic dilatation of the pulmonary artery is uncommon. Approximately two thirds of patients with Noonan syndrome have PS due to dysplastic valves.

A bicuspid valve is found in as many as 90% of patients with tetralogy of Fallot, whereas it is rare in individuals with isolated valvar PS.

With severe valvular PS, subvalvular right ventricular hypertrophy can cause infundibular narrowing and contribute to the right ventricular outflow obstruction. This often regresses after correction of valvular stenosis.

With severe PS and decreased right ventricular chamber compliance, cyanosis can occur from right-to-left shunting if a concomitant patent foramen ovale, atrial septal defect, or ventricular septal defect is present.

Subvalvular pulmonic stenosis

Subvalvular PS occurs as a narrowing of the infundibular or subinfundibular region, often with a normal pulmonic valve. This condition is present in individuals with tetralogy of Fallot and can also be associated with a ventricular septal defect (VSD).

Double-chambered right ventricle is a rare condition associated with fibromuscular narrowing of the right ventricular outflow tract with right ventricular outflow obstruction at the subvalvular level.

Peripheral pulmonary stenosis

Peripheral pulmonary stenosis (PPS) can cause obstruction at the level of the main pulmonary artery, at its bifurcation, or at the more distal branches. PPS may occur at a single level, but multiple sites of obstruction are more common. PPS may be associated with other congenital heart anomalies such as valvular PS, atrial septal defect (ASD), VSD, or patent ductus arteriosus (PDA); 20% of the patients with tetralogy of Fallot have associated PPS.

Functional or physiologic PPS is a common cause of a systolic murmur in infants. It occurs in both premature and full-term infants; with time, the pulmonary artery grows, and the murmur usually disappears within a few months.

Poststenotic dilatation occurs with discrete segmental stenosis but is absent if the stenotic segment is long or if the pulmonary artery is diffusely hypoplastic.

PPS is associated with various inherited and acquired conditions including rubella and the Alagille, cutaneous laxa, Noonan, Ehlers-Danlos, and Williams syndromes.

PreviousNextEpidemiologyFrequencyUnited States

PS is a common form of congenital heart disease that occasionally is diagnosed for the first time in adulthood. Isolated valvular PS comprises approximately 10% of all congenital heart disease.

Mortality/Morbidity

Except for critical stenosis in neonates, survival is the rule in congenital PS.

The long-term course of patients with mild PS is indistinguishable from that of the unaffected population. Mild PS does not tend to progress in severity; rather, pulmonic valve orifice size usually increases with body growth. However, untreated severe PS may result in outflow obstruction that progresses over a period of years; 60% of patients with severe PS require intervention within 10 years of diagnosis.

Sex

A slight female predominance exists.

PreviousProceed to Clinical Presentation , Pulmonic Stenosis

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Tricuspid Stenosis

Background

Tricuspid valve dysfunction can result from morphological alterations in the valve or from functional aberrations of the myocardium. Tricuspid stenosis is almost always rheumatic in origin and is generally accompanied by mitral and aortic valve involvement.[1]

Most stenotic tricuspid valves are associated with clinical evidence of regurgitation that can be documented by performing a physical examination (murmur), echocardiography, or angiography. Stenotic tricuspid valves are always anatomically abnormal, and the cause is limited to a few conditions. With the exceptions of congenital causes or active infective endocarditis, tricuspid stenosis takes years to develop.[2, 3]

A representation of a stenotic tricuspid valve. This image demonstrates fusion of the commissures (shown as dotted lines). NextPathophysiology

Tricuspid stenosis results from alterations in the structure of the tricuspid valve that precipitate inadequate excursion of the valve leaflets. The most common etiology is rheumatic fever, and tricuspid valve involvement occurs universally with mitral and aortic valve involvement. With rheumatic tricuspid stenosis, the valve leaflets become thickened and sclerotic as the chordae tendineae become shortened. The restricted valve opening hampers blood flow into the right ventricle and, subsequently, to the pulmonary vasculature. Right atrial enlargement is observed as a consequence. The obstructed venous return results in hepatic enlargement, decreased pulmonary blood flow, and peripheral edema. Other rare causes of tricuspid stenosis include carcinoid syndrome, endocarditis, endomyocardial fibrosis, systemic lupus erythematosus, and congenital tricuspid atresia.[4, 2, 3]

In the rare instances of congenital tricuspid stenosis, the valve leaflets may manifest various forms of deformity, which can include deformed leaflets, deformed chordae, and displacement of the entire valve apparatus. Other cardiac anomalies are usually present.[1]

PreviousNextEpidemiologyFrequencyUnited States

Tricuspid stenosis is rare, occurring in less than 1% of the population. While found in approximately 15% of patients with rheumatic heart disease at autopsy, it is estimated to be clinically significant in only 5% of these patients. The incidence of the congenital form of the disease is less than 1%.

International

Tricuspid stenosis is found in approximately 3% of the international population. It is more prevalent in areas with a high incidence of rheumatic fever. The congenital form of the disease is rare and true incidence is not available.

Mortality/Morbidity

The mortality associated with tricuspid stenosis depends on the precipitating cause. The general mortality rate is approximately 5%.

Race

No racial predisposition is apparent.

Sex

Tricuspid stenosis is observed more commonly in women than in men, similar to mitral stenosis of rheumatic origin. The congenital form of the disease has a slightly higher male predominance.

Age

Tricuspid stenosis can present as a congenital lesion or later in life when it is due to some other condition. The congenital form accounts for approximately 0.3% of all congenital heart disease cases. The frequency of tricuspid stenosis in the older population, due to secondary causes, ranges from 0.3-3.2%.

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